High capacity air-cooling system for electronic apparatus and associated methods

ABSTRACT

An improved air-cooling system for high performance, high density electronic equipment comprises, in one embodiment, a single fan having a radial impeller, a baffle having an inlet portion to efficiently direct air into the fan intake, and a two-tiered outlet plenum to direct one airflow specifically at the highest heat-generating components and another airflow at all components. The air-cooling system is designed to provide maximum cooling for a low-height, high heat-generating electronics module such as a server. By using only a single fan that is matched to the low resistance airflow characteristics of the baffle, the air-cooling system offers significant advantages over multi-fan systems. Also described are a computer server and methods of making heat-dissipation equipment.

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates generally to heat dissipation inelectronic apparatus. More particularly, the present invention relatesto an improved air-cooling system for high density electronic equipment.

BACKGROUND OF THE INVENTION

[0002] Computer networks, such as the Internet, utilize high performancecomputer systems called “servers”. Servers typically have highperformance processors and contain hardware and software capable ofhandling large amounts of data. Servers provide a large number ofcomputer users with access to large stores of information. For example,servers are used to host web sites that can be accessed by manycomputers via the Internet.

[0003] One or more server components are often housed within a serverhousing or “server rack”. Server racks are typically box-like structuresor cabinets that contain a number of removable electronic modules orelectronic trays (“e-trays”). Each e-tray can be a different server, oreach e-tray can hold one or more components of a server. Servercomponents can include electronic modules, for example, for processors,disk drives (such as floppy disk drives, hard drives, compact disk (CD)drives, and digital video disk (DVD) drives), random access memory(RAM), network interfaces and controllers, SCSI (small computer systemsinterface) bus controllers, video controllers, parallel and serialports, power supplies, and so forth.

[0004] There is an ever increasing demand by computer users for higherperformance levels in computer equipment, such as servers. Because suchequipment operates at higher and higher power levels, there is, as adirect consequence, an ever accelerating requirement to dissipate thethermal energy or heat produced by the equipment.

[0005] For example, a server having dual high-performance processors,such as processors from the Intel® 64-bit Itanium™ family of processors(available from Intel Corporation, Santa Clara, Calif., U.S.A.), canproduce a significant amount of heat, which can be in the order ofseveral hundred watts of heat. To compound the problem, when a server atthis performance level is packaged in an industry-standard “1U” heightserver (i.e. only 1.75 inches (4.445 cm) in height), heat dissipationcan become a significant concern. If the heat is not adequatelydissipated, the server equipment could be damaged, or the processorscould be automatically throttled down to operate at a slower speed thantheir nominal rating.

[0006] Many air-cooled systems have been used to cool electronicsequipment, including computer equipment, in the past. In the past,relatively high performance electronic equipment generally requiredlarger, more complex, and more powerful cooling solutions, as well as acorresponding increase in the size of the equipment cabinet or othertype of equipment housing.

[0007] For example, high performance computer equipment required anincrease in the cabinet height to accommodate axial fans having largerpropellers, as well as a greater number of axial fans per chassis. It isnot unusual to see a half-dozen or more axial-type fans deployed on asingle high performance chassis.

[0008] These fans, and their associated airflow ducting, can consume anenormous amount of real estate on the chassis. They also contributesubstantially to the cost, complexity, size, and height of the computersystem, not to mention the additional noise that they produce due to thefact they typically run at high RPM, e.g. exceeding 10,000 RPM.

[0009] Floor space for server racks is expensive, and it is desirable topack as much computer performance into as small a space as possible.However, for the reasons set forth above, this can create significantheat dissipation problems.

[0010] For the reasons stated above, and for other reasons stated belowwhich will become apparent to those skilled in the art upon reading andunderstanding the present specification, there is a significant need inthe art for improved air-cooling systems for high performance electronicequipment that do not suffer the disadvantages of the prior artair-cooling systems, and for associated methods of making heatdissipation apparatus for high performance, high density electronicequipment.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a perspective view of an air-cooled electronics tray, inaccordance with one embodiment of the invention;

[0012]FIG. 2 is a top view of the air-cooled electronics trayillustrated in FIG. 1;

[0013]FIG. 3 is a cross-sectional view, taken along dashed line 30 ofFIG. 2, of the air-cooled electronics tray illustrated in FIG. 2;

[0014]FIG. 4 is a cross-sectional view, taken along dashed line 40 ofFIG. 2, of the air-cooled electronics tray illustrated in FIG. 2;

[0015]FIG. 5 is an exploded perspective view of the baffle and radialfan illustrated in FIG. 2;

[0016]FIG. 6 is a more detailed wireframe perspective view of the bafflemembers and the radial fan illustrated in FIG. 5;

[0017]FIG. 7 is a simplified perspective view of the air-cooledelectronics tray illustrated in FIG. 1, showing the outlet portion ofthe baffle as viewed from the exit sides of the exit plenums;

[0018]FIG. 8 is a rear perspective view of a baffle member shown in FIG.5;

[0019]FIG. 9 is a top view of an air-cooled electronics tray having adifferent baffle, in accordance with another embodiment of theinvention;

[0020]FIG. 10 is a perspective view of the inlet portion of the baffleof the air-cooled electronics tray illustrated in FIG. 9;

[0021]FIG. 11 is a cross-sectional view, taken along dashed line 70 ofFIG. 10, of the baffle illustrated in FIG. 10; and

[0022]FIG. 12 is a flow diagram illustrating a method of making heatdissipation apparatus for cooling an electronic assembly or other typeof electronic chassis, in accordance with one embodiment of theinvention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0023] In the following detailed description of embodiments of theinvention, reference is made to the accompanying drawings which form apart hereof, and in which is shown by way of illustration specificpreferred embodiments in which the inventions may be practiced. Theseembodiments are described in sufficient detail to enable those skilledin the art to practice the invention, and it is to be understood thatother embodiments may be utilized and that mechanical, compositional,structural, electrical, and procedural changes may be made withoutdeparting from the spirit and scope of the present invention. Thefollowing detailed description is, therefore, not to be taken in alimiting sense, and the scope of the present invention is defined onlyby the appended claims.

[0024] The present invention provides a solution to the need toefficiently and quietly dissipate heat that is generated by highperformance electronic equipment, and to do so in a manner that isrelatively simple and inexpensive, and that does not increase chassisheight or consume an undue amount of chassis real estate. Variousembodiments are illustrated and described herein.

[0025]FIG. 1 is a perspective view of an air-cooled electronics tray 1,in accordance with one embodiment of the invention. Electronics tray(“e-tray”) 1 comprises a chassis that includes side panels 2 and 3,front panel 4, rear panel 5, top panel 26 (FIG. 3), and bottom panel 28(FIG. 3). In one embodiment, e-tray is approximately 1.75″ (4.445 cm)high, 17″ (43 cm) wide, and 24″ (61 cm) deep. A 1U-type chassis is astandard 1.75″ (4.445 cm) in height.

[0026] E-tray 1 includes electronic apparatus in the form of electroniccomponents, such as hard drive 7, memory boards 8, printed circuit board(PCB) 13, and mezzanine board 14. PCB 13 and mezzanine board 14 caninclude any number of electronic devices, including integrated circuits(IC's) and discrete devices. The IC's can include memory chips,chipsets, and one or more processor chips.

[0027] In one embodiment, e-tray 1 comprises a pair of high performance64-bit processors from the Intel® Itanium™ family of processors. Theseprocessors typically can operate at 1 Gigahertz clock speeds or higher.However, any type of high performance processor(s) could be used one-tray 1. Further, more than two or fewer than two processors could beused. As used herein, “processor” means any type of computationalcircuit, such as but not limited to a microprocessor, a microcontroller,a complex instruction set computing (CISC) microprocessor, a reducedinstruction set computing (RISC) microprocessor, a very long instructionword (VLIW) microprocessor, a graphics processor, a digital signalprocessor, a communications processor, an application specificintegrated circuit (ASIC), or any other type of processor or processingcircuit.

[0028] At least one set of heat sink fins 12 or other type of thermalinterface arrangement, such as a heat pipe or heat spreader, is providedto conduct heat from devices that produce high levels of heat. Fins 12conduct heat directly from the heat-generating devices to ambient airsurrounding the devices. However, unless the chassis includes amechanism for ridding itself of this increase in ambient heat, heat willbuild up to an undesirable level within the chassis, impacting theperformance and life of electronic components on the chassis.

[0029] Thus e-tray 1 comprises heat-dissipation apparatus. In oneembodiment, the heat-dissipation apparatus comprises a fan indicatedgenerally by reference number 11, and an arrangement of baffles. Fan 11includes a motor housing 18 (FIG. 3) and a radial impeller 17. Radialimpeller 17 can be of the “squirrel cage” variety, and its individualvanes or blades can be either forward-curved or reverse-curved relativeto the direction of spin. Radial impeller 17 is coupled to an inner wall16 that, in turn, is coupled to fan motor shaft 19 (FIG. 3).

[0030] In one embodiment, fan 11 is a high-output radial impeller fanproducing approximately 70 cubic feet (6.5 cubic meters) per minute.Radial fans generally run at much lower RPM (e.g. only 2800 RPM) thanaxial fans (typically greater than 10,000 RPM). This also significantlyincreases the lifespan of a radial fan over an axial fan running at muchhigher RPM. However, the invention is not to be construed as limited tothe use of a radial impeller fan, and any other type of fan that cangenerate comparable airflow within the geometrical constraints of thechassis can be used.

[0031] Fan 11 draws in outside air through a grill 6 in front panel 4.Grill 6 can serve as an electromagnetic interference (EMI) grid.Alternatively, a separate EMI grid (not shown) can be employed inconjunction with grill 6.

[0032] A baffle, indicated generally by reference number 100, directsair into fan 11 and from there out to the electronic components on PCB13 and on mezzanine 14 that require cooling. As seen better in FIG. 2,baffle 100 comprises an inlet portion, generally indicated by referencenumber 10, and an outlet portion, generally indicated by referencenumber 20. Although baffle 100 is described as comprising an inletportion 10 and an outlet portion, baffle 100 can be implemented in anyappropriate number of physical elements, including separate inlet andoutlet baffles, a single integrated baffle structure having inlet andoutlet portions, and so forth. Baffle 100 can be made of any suitablematerial, such as molded plastic, fiberglass, or metal.

[0033] Referring once again to FIG. 1, fan 11 pumps air into outletportion 20, indicated generally by reference number 20. Outlet portion20 comprises two exit plenums 21 and 22. Exit plenums 21 and 22 areformed, in one embodiment, such that their cross-sectional areasincrease with increasing distance from fan 11, in a shape that issomewhat analogous to a nautilus shell. This shape minimizes backpressure and turbulence within exit plenums 21 and 22, enabling them toconduct air more efficiently.

[0034] In the embodiment shown in FIG. 1, a first portion of the airbeing pumped by fan 11 goes into exit plenum 21, and a second portion ofthe air goes into exit plenum 22. This is seen more clearly in FIG. 3 tobe discussed below.

[0035] Continuing with FIG. 1, the portion of the air going through exitplenum 21 emanates from its air outlet in the direction indicated byarrows 23 and flows through heat sink fins 12 of the processor packages(33-34, FIG. 5), carrying away heated ambient air and exiting thechassis through holes in rear panel 5 in the direction indicated byarrows 25. The air leaving exit plenum 21 is thus directed at chassiscomponents that are generating a relatively large amount of heat.

[0036] Similarly, the portion of the air going through exit plenum 22emanates from its air outlet in the direction indicated by arrows 24 andflows over memory boards 8 and over other heat-generating components onmezzanine 14 and on PCB 13, carrying away heated ambient air and exitingthe chassis through holes in rear panel 5 in the direction indicated byarrows 25.

[0037] Baffle 100 and fan 11 are individually available from TorringtonResearch Company, Torrington, Conn., U.S.A., whose URL is WWW.TRCT.com.

[0038]FIG. 2 is a top view of the air-cooled electronics tray 1illustrated in FIG. 1. As mentioned earlier, baffle 100 comprises aninlet portion 10 and an outlet portion 20. If one follows a geometricalline (such as dashed line 30) from grill 6 inward to PCB 13 andmezzanine 14, it is seen that inlet portion 10 and outlet portion 20overlap to a certain extent, due to the particular geometry of inletportion 10 and outlet portion 20. However, in other embodiments of abaffle, there may be no overlap, depending upon the particular geometryof the baffle.

[0039] The shape of exit plenums 21 and 22 of outlet portion 20 can beseen in FIG. 2. Exit plenum 21 directs air through its end section 29 atheat sink fins 12 of the processors (not shown, but positioned beneathheat sink fins 12). Thus exit plenum 21 directs approximately half ofthe output of fan 11 at chassis components that are generating asignificant amount of heat.

[0040] Exit plenum 22 directs air through an end section having a widththat is equivalent to the width of the chassis minus the width of theend section 29 of exit plenum 21. Exit plenum 22 directs approximatelyhalf of the output of fan 11 at chassis components that are positionedbetween exit plenum 22 and rear panel 5. This includes, for example,memory boards 8 and mezzanine board 14, as well as to some extent thechassis components that are positioned between exit plenum 21 and rearpanel 5, because the air exiting from exit plenums 21 and 22 mixestogether before it exits through vent holes in rear panel 5.

[0041]FIG. 3 is a cross-sectional view, taken along dashed line 30 ofFIG. 2, of the air-cooled electronics tray 1 illustrated in FIG. 2.Dashed line 30 passes through the center of fan motor shaft 19 and themotor housing 18 of fan 11. One end of fan motor shaft 19 is coupled toa motor (not shown for simplicity of illustration) within fan motorhousing 18, and the other end of fan motor shaft 19 is coupled to innerwall 16 of radial impeller. Inner wall 16 is, in turn, coupled to a basemember 31, to which a plurality of vanes or blades 32 are attached toform radial impeller 17.

[0042] Seen in FIG. 3 are steps 41 and 42 of inlet portion 10 of baffle100. A first portion of the incoming airflow, represented by arrows 15,passes through grill 6 straight into opening 45 (FIG. 1) of fan 11 (FIG.1), while other portions of the incoming airflow move through grill 6and then upward over one or both steps 41 and 42 before entering opening45. A portion 38 of baffle 100 can make contact with top panel 26 toprevent air from recirculating from the exit of baffle 100 back toopening 45.

[0043] Also seen in FIG. 3 is exit plenum 21. As explained above, andseen more clearly in FIG. 3, exit plenum 21 receives air from the upperportion of radial impeller 17. Exit plenum 22 is not viewable in FIG. 3;however, a static chamber 35 can be seen (also seen in FIGS. 5, 6, and8). Static chamber 35 does not conduct air; however, it can be used, forexample, to house cables or other chassis components that do notgenerate significant amounts of heat.

[0044] Heat sink fin 12 is affixed to a processor package (34, FIG. 7)situated on PCB 13. Air exiting from both exit plenums 21 and 22 (seenin FIG. 1) blows through the segment of PCB 13 to which the processorpackages are mounted.

[0045]FIG. 4 is a cross-sectional view, taken along dashed line 40 ofFIG. 2, of the air-cooled electronics tray 1 illustrated in FIG. 2.Dashed line 40 passes through the center of fan motor shaft 19 and themotor housing 18 of fan 11.

[0046] Also seen in FIG. 4 are steps 41 and 42 of inlet portion MMM ofbaffle 100. In addition, the upper ends of heat sink fins 12 can beseen.

[0047]FIG. 5 is an exploded perspective view of the baffle 100 andradial fan 17 illustrated in FIG. 2. Baffle 100 can be formed in adual-element configuration that includes a first baffle member 51 and asecond baffle member 52. Baffle members 51 and 52, when assembled in anorientation along dashed line 103, together form baffle 100, and theysurround fan 11.

[0048] Baffle member 51 includes inlet step 41, opening 45, and exitplenum 21. Baffle member 52 includes inlet step 42, opening 46, and exitplenum 22. Openings 45 and 46 can have the same diameters. Baffle member52 also includes a static chamber segment 27 that has several staticchambers 35. Static chambers 35 do not conduct airflow. Static chambers35 prevent recirculation of air back to the inlet of fan 11, and theycan be used for storing miscellaneous chassis components.

[0049]FIG. 6 is a more detailed wireframe perspective view of the bafflemembers 51 and 52 and of radial fan 11 illustrated in FIG. 5. Theexterior “skins” of exit plenum 21 of baffle member 51 and of staticchamber segment 27 of baffle member 52 have been removed to show theinterior detail. Chamber 36 within baffle member 52 does not conductairflow and can be sealed. This area can serve as a support for exitplenum 21 of baffle member 51, when baffle members 51 and 52 areassembled into baffle 100.

[0050]FIG. 7 is a simplified perspective view of the air-cooledelectronics tray 1 illustrated in FIG. 1, showing the outlet portion ofbaffle 100 as viewed from the exit sides of exit plenums 21 and 22.

[0051] As described earlier, exit plenum 21 directs air through its endsection at heat sink fins 12 of processor packages 33 and 34. Exitplenum 22 directs air through an end section having a width that isequivalent to the width of the chassis minus the width of the endsection of exit plenum 21. Exit plenum 22 directs approximately half ofthe output of fan 11 at chassis components that are positioned anywherebetween exit plenum 22 and the rear edge 9 of the chassis, because theair exiting from exit plenums 21 and 22 mixes together before it exitsthrough vent holes in rear panel 5 (FIG. 1).

[0052]FIG. 8 is a rear perspective view of baffle member 52 shown inFIG. 5. This view is from essentially the same perspective as the exitplenum 22 is depicted in FIG. 7. Baffle member 52 includes an opening 37in exit plenum 22. Also seen in FIG. 8 are several static chambers 35 ofstatic chamber segment 27.

[0053]FIG. 9 is a top view of an air-cooled electronics tray 101 havinga different baffle 60, in accordance with another embodiment of theinvention. In the embodiment shown in FIG. 9, all elements of theelectronics tray 101 can be substantially similar to those depicted inFIGS. 1 and 2 except for baffle 60.

[0054] Baffle 60 directs air, represented by arrows 71, into opening 68,through fan 11, and out an exit plenum in the direction indicated byarrows 72 towards chassis components requiring cooling. Baffle 60 willnow be described in greater detail regarding FIG. 10 immediately below.

[0055]FIG. 10 is a perspective view of the inlet portion of baffle 60 ofthe air-cooled electronics tray 101 illustrated in FIG. 9. Baffle 60comprises substantially vertical sides 61 and 62, and it furthercomprises a raised platform 67. A back wall 63 extends along the back ofplatform 67. Side 61, side 62, back wall 63, platform 67, and the toppanel 26 (FIG. 3) form an intake plenum that bounds the air that isdrawn in by fan 11. Airflow 72 is prevented from being recirculated backto fan 11 by this structure.

[0056] Platform 67 comprises a large opening 68 juxtaposed to the intakeof fan 11. Opening 68 has a rounded lip 69 in one embodiment.

[0057] The approach area 64 to baffle 60 comprises an angled ramp 65.Ramp 65 can have a step 66 around its outer periphery. Ramp 65 is formedin an arc about one side of opening 68. Ramp 65 decreases thecross-sectional area of the intake plenum in relation to the distancefrom the opening 68.

[0058] In operation, air is drawn into the approach area 64 of baffle60, and it flows in the direction of arrows 71 over step 66, up ramp 66onto platform 67, through opening 68, and into the intake of fan 11.

[0059] As seen in FIG. 1, the periphery of grill 6 in front panel 4(FIG. 1) bounds a relatively small cross-sectional area through whichall of the intake air must pass. To minimize the amount of work that fan11 must perform, it is desirable to minimize the length of the region ofnarrowing cross-section that runs from grill 6 to platform 67. Byproviding an angled ramp 65, the region of narrowing cross-section iskept to a minimum, and intake air is efficiently funneled into theintake of fan 11.

[0060] Employing a relatively short region of small cross-sectionimproves air intake performance over a non-ramped inlet to the baffle,in part because it offers less overall resistance to incoming airflow,and in part because back-pressure, vortices, eddys, and otherundesirable airflow disturbances are minimized through the use of ashort angled ramp 65, as opposed to a long, non-angled intake region ora rectangular intake region.

[0061] In addition, an angled ramp 65 also enables EMI containment inthe form of a grill or mesh to be positioned in the area of greatestcross-sectional area, not in a region of small cross-sectional area.Sufficient EMI containment can thus be provided while concurrentlyminimizing its effect on air flowing into the intake of fan 11.

[0062] Baffle 60 can be made of any suitable material, such as moldedplastic, fiberglass, or metal.

[0063]FIG. 11 is a cross-sectional view, taken along dashed line 70 ofFIG. 10, of the baffle 60 illustrated in FIG. 10. The profile of angledramp 65 can clearly be seen in FIG. 11, as can the lip 69 around opening68 (FIG. 10) of platform 67 of baffle 60. Radial impeller 17 comprises aplurality of blades or vanes 32 that are coupled to base member 31 ofradial impeller 17.

[0064]FIG. 12 is a flow diagram illustrating a method of making heatdissipation apparatus for cooling an electronic assembly or other typeof electronic chassis, in accordance with one embodiment of theinvention. The method begins at 200.

[0065] In 202, a chassis having a plurality of heat-generatingcomponents (e.g. IC's and/or discrete devices such as resistors,capacitors, and inductors) is provided. In one embodiment, a computerserver is provided. In another embodiment, a 1U e-tray is provided thatcan be any type of electronic equipment, including a computer component.The chassis can be relatively low in height; e.g. in one embodiment thewidth-to-height ratio of the chassis is approximately 9 or greater.However, the present invention also performs well for width-to-heightratios that are less than 9, i.e. for chassis that are relatively highsuch as, without limitation, 4U or 7U chassis. The geometry of the fanand of the inlet and outlet portions of the baffle can be appropriatelyadjusted.

[0066] While the embodiment shown in the figures is a server that ispositioned in a horizontal rack, the present invention can also be usedin vertical-type racks. For example, the exit plenums of the outletportion of the baffle could be arranged side-by-side vertically ratherthan double-tiered horizontally.

[0067] In 204, a fan is mounted on the chassis. The fan can be of anytype, such as a radial impeller fan, an axial impeller fan, or any othersuitable type. In one embodiment, a single radial impeller fan is usedto quietly, efficiently, cost-effectively, and reliably cool an entireserver chassis or e-tray of the 1U form factor. However, in otherembodiments more than one fan can be used.

[0068] In 206, a baffle is mounted on the chassis. In one embodiment,the baffle is constructed as one unit encompassing both an inlet baffleand an outlet baffle. In such an embodiment, the baffle has an inletcoupled to the fan and an outlet that is directed at the electroniccomponents of the chassis. In another embodiment, as discussed earlier,separate inlet and outlet baffles can be utilized, and in such anembodiment the inlet baffle is coupled to the fan and directs air intothe fan intake, and the outlet baffle directs air at the electroniccomponents of the chassis.

[0069] Still referring to 206, the outlet can include a first portionthat is directed to electronic components that are generating arelatively large amount of heat, and a second portion that is directedat an area of the chassis that does not necessarily include such highheat generating components. Various alternatives are possible. Forexample, in one embodiment, the second portion can direct air towardselectronic components over the entire chassis, or it could direct aironly towards all electronic components except for those covered by thefirst portion, or it could direct air at a subset of the remainingelectronic components, leaving a portion of the electronic components(e.g. low heat generating components) that are not covered by either thefirst or second portions. In 208, the method ends.

[0070] The operations described above with respect to the methodillustrated in FIG. 12 can be performed in a different order from thatdescribed herein. Also, it should be understood that although an “End”block is shown for the method, it may be continuously performed.

Conclusion

[0071] The present invention provides for heat-dissipation apparatus forhigh density electronic equipment, which in one embodiment comprises arelatively low-height server, such as a 1U server. In one embodiment,the ratio of width to height of the server is approximately 9 orgreater; however, other width-to-height ratios are possible.

[0072] In one embodiment, a single fan, such as a radial impeller fan,is coupled to an inlet baffle, or to an inlet portion of a baffle, thatprovides efficient air flow into the fan, and to an outlet baffle, or toan outlet portion of a baffle, that directs a relatively high volume ofair over heat-generating components on a chassis of the electronicequipment. This air-cooling arrangement is highly efficient and iscapable of cooling a 1U server housing a pair of high-performance 64-bitprocessors, such as processors from Intel's Itanium™ family ofprocessors.

[0073] Other embodiments described herein include an electronicapparatus that includes a heat-dissipation apparatus essentially asdescribed above; an inlet baffle having a cross-sectional area thatincreases with the distance from a fan inlet to which it is coupled andfurther having a ramp to the fan inlet; and methods of making anair-cooled chassis.

[0074] Various embodiments of the invention enable high densityelectronic apparatus to operate reliably and quietly within its thermalperformance specifications.

[0075] As shown herein, the present invention can be implemented in anumber of different embodiments. Other embodiments will be readilyapparent to those of ordinary skill in the art. The elements, materials,geometries, dimensions, and sequence of operations can all be varied tosuit the particular requirements of the electronic apparatus with whichvarious implementations of the invention may be used.

[0076] The invention should not be construed as restricted to servers or1U servers, and it may find application in any type of electronicassembly. For example, it can be used for telecommunications equipment,power industry equipment, industrial equipment, radio and televisionbroadcasting equipment, aerospace and military equipment, maritimeequipment, automotive equipment, and personal entertainment equipment(e.g., televisions, radios, stereos, tape and compact disc players,video cassette recorders, MP3 (Motion Picture Experts Group, Audio Layer3) players, etc.), and the like. Thus, as used herein, the terms“server” or “electronic assembly” are intended to mean any type ofelectronic assembly structure.

[0077] The terms “top”, “bottom”, “front”, and “back” are to beunderstood as relative terms, and it should be understood that the scopeof the invention includes corresponding elements in structures that maybe inverted, turned end-for-end, mirrored, or rotated through 90 degreesor through any other angle, relative to those shown in the figures anddescribed herein.

[0078] The above-described choice of materials, geometry, structure, andassembly operations can all be varied by one of ordinary skill in theart to optimize heat dissipation in electronic assemblies. Theparticular implementation of the invention is very flexible in terms ofthe orientation, size, number, and composition of its constituentelements. Various embodiments of the invention can be implemented usingany one or more of various geometrical and functional arrangements ofradial or axial fans, inlet and/or outlet baffles or ducts, andcombinations thereof, to achieve the advantages of the presentinvention.

[0079] The figures are merely representational and are not drawn toscale. Certain proportions thereof may be exaggerated, while others maybe minimized. FIGS. 1-8 are intended to illustrate variousimplementations of the invention that can be understood andappropriately carried out by those of ordinary skill in the art.

[0080] Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat any arrangement that is calculated to achieve the same purpose maybe substituted for the specific embodiment shown. This application isintended to cover any adaptations or variations of the presentinvention. Therefore, it is manifestly intended that this invention belimited only by the claims and the equivalents thereof.

What is claimed is:
 1. Heat-dissipation apparatus for high densityelectronic equipment comprising: a radial impeller fan having a fanintake; and a baffle comprising an inlet plenum having a cross-sectionalarea that increases with distance from the fan, and the baffle furthercomprising a ramp coupled to the fan intake.
 2. The heat-dissipationapparatus recited in claim 1, wherein the electronic equipment comprisesa dual-processor server.
 3. The heat-dissipation apparatus recited inclaim 1, wherein the electronic equipment comprises a relativelylow-height server.
 4. The heat-dissipation apparatus recited in claim 3,wherein the ratio of width to height of the server is 9 or greater. 5.The heat-dissipation apparatus recited in claim 3, wherein the server isa 1U server.
 6. The heat-dissipation apparatus recited in claim 1,wherein the baffle further comprises an exit plenum having across-sectional area that increases with distance from the fan.
 7. Theheat-dissipation apparatus recited in claim 6, wherein the bafflecomprises an additional exit plenum having a cross-sectional area thatincreases with distance from the fan, and wherein the exit plenum andthe additional exit plenum each comprise an air outlet, one of which isdirected at components generating a relatively large amount of heat, andone of which is directed at an area of the electronic equipment thatdoes not necessarily include such components.
 8. Electronic apparatuscomprising: a chassis comprising heat-generating electronic components;and heat-dissipation apparatus comprising: a radial impeller fan havinga fan intake; and a baffle comprising an inlet plenum having across-sectional area that increases with distance from the fan, and thebaffle further comprising a ramp coupled to the fan intake.
 9. Theelectronic apparatus recited in claim 8, wherein the electroniccomponents include at least two processors.
 10. The electronic apparatusrecited in claim 8, wherein the chassis comprises a relativelylow-height server.
 11. The electronic apparatus recited in claim 10,wherein the ratio of width to height of the server is 9 or greater. 12.The electronic apparatus recited in claim 10, wherein the server is a 1Userver.
 13. A server comprising: a chassis comprising heat-generatingelectronic components; and heat-dissipation apparatus comprising: aradial impeller fan having a fan intake; and a baffle comprising aninlet plenum having a cross-sectional area that increases with distancefrom the fan, and the baffle further comprising a ramp coupled to thefan intake.
 14. The server recited in claim 13, wherein the electroniccomponents include a plurality of processors.
 15. The server recited inclaim 13, wherein the processors are 64-bit processors and operate at 1Gigahertz clock speed or higher.
 16. The server recited in claim 13,wherein the chassis comprises a relatively low-height server.
 17. Theserver recited in claim 16, wherein the ratio of width to height of theserver is 9 or greater.
 18. The server recited in claim 16, wherein theserver is a 1U server.
 19. A 1U electronics assembly comprising: achassis comprising heat-generating electronic components; andheat-dissipation apparatus comprising: a single fan having a fan intake;and a baffle comprising an inlet plenum coupled to the fan intake and anoutlet plenum directed at the electronic components.
 20. The electronicsassembly recited in claim 19, wherein the fan comprises a radialimpeller fan.
 21. The electronics assembly recited in claim 19, whereinthe electronic components include a plurality of processors.
 22. Theelectronics assembly recited in claim 21, wherein the processors are64-bit processors and operate at 1 Gigahertz clock speed or higher. 23.A method of making an air-cooled chassis comprising: providing a chassiscomprising heat-generating electronic components, the chassis having awidth-to-height ratio of 9 or greater; mounting a single fan on thechassis; and mounting a baffle on the chassis, the baffle comprising aninlet coupled to the fan and an outlet directed at the electroniccomponents.
 24. The method recited in claim 23, wherein the fancomprises a radial impeller.
 25. The method recited in claim 23, whereinthe fan comprises an axial impeller.
 26. The method recited in claim 23,wherein the baffle comprises a first portion directed at componentsgenerating a relatively large amount of heat, and a second portiondirected at an area of the chassis that does not necessarily includesuch components.
 27. A method of making an air-cooled chassiscomprising: providing a 1U chassis comprising heat-generating electroniccomponents; mounting a single fan on the chassis; and mounting a baffleon the chassis, the baffle comprising an inlet coupled to the fan and anoutlet directed at the electronic components.
 28. The method recited inclaim 27, wherein the fan comprises a radial impeller.
 29. The methodrecited in claim 27, wherein the fan comprises an axial impeller. 30.The method recited in claim 27, wherein the baffle comprises a firstportion directed at components generating a relatively large amount ofheat, and a second portion directed at an area of the chassis that doesnot necessarily include such components.
 31. An intake bafflecomprising: a platform comprising an opening to be juxtaposed to a fanintake; and a plenum coupled to the platform and comprising a ramp todecrease a cross-sectional area of the plenum in relation to thedistance from the opening.
 32. The intake baffle recited in claim 31,wherein the ramp forms an arc about one side of the opening.
 33. Theintake baffle recited in claim 31, wherein the ramp comprises a step.